Security film systems of that kind are wide-spread and are used in the form of hot stamping films or protective laminate films in the most widely varying areas.
Irrespective of their area of use, whether as a security element for banknotes, check or credit cards or for identity documents, the security film systems known from the state of the art are generally of a substantially identical layer structure. In that respect, hot stamping or laminate films of that kind generally have an adhesive layer portion for fixing on a substrate, that is to say an article to be decorated or protected. Arranged on that adhesive layer portion is a transfer layer which is composed of one or more layer portions and includes corresponding security elements. In that case, metallised or non-metallised diffraction structures can be contained in the layer constitution, wherein the individual layer portions can also be provided over the full surface area or part thereof and can be of varying colors. Frequently those layer portions are formed by differing lacquers which are preferably applied by means of printing processes. It is possible in that way to produce decorative patterns or security elements in accurate register relationship. The transfer layer may further include lacquer layer portions which can be irreversibly modified subsequently, for example by irradiation with a laser.
Security film systems of that kind are generally known in regard to the structure of the transfer layer and were the subject of numerous patent applications in recent times.
The specified security film systems in that case are usually provided with thermoplastic adhesive systems. Those security film systems are transferred on to the article to be protected, for example a personalised pass page or the like, by means of pressure and temperature. In that procedure, the adhesive is caused to melt by means of the action of temperature in the operation of transferring the system on to the article. In that case the adhesive is physically anchored in the substrate to be decorated or provided with a security element, or the surface of the material of the substrate, and provides for the necessary bonding adhesion after the arrangement has cooled down. No chemical reaction takes place in that situation. A particular disadvantage of those adhesive systems however is that they can be reversibly melted at any time and thus the transfer layer containing the security element can be easily detached by heating and applied to another substrate. Such thermoplastic bonds are thus a potential weakness in security film systems, by virtue of the thermoplastic properties of such bonds.